The present invention relates generally to a means for recirculating exhaust gas through an engine.
Exhaust gas is commonly recirculated through an internal combustion engine in order to improve the exhaust gas quality and fuel efficiency of the engine. In general, a portion of the exhaust from the engine is siphoned off the main exhaust stream downstream of the engine and re-routed to a location upstream of the engine where it is mixed with the fresh air supply. The mixture of fresh air and the recirculated exhaust gas is then supplied to the engine. The degree to which fuel efficiency and exhaust gas quality of the engine are improved depends on, among other things, the location where the exhaust gas is injected into the fresh air stream and the manner in which it is injected.
One possible location for introducing the exhaust gas into the fresh air stream is to inject the exhaust gas at some point on the intake manifold. The are myriad possible locations on an intake manifold where the exhaust gas can be injected, and the resultant improvements in fuel efficiency and exhaust gas quality are equally varied. The flow conditions vary greatly throughout an intake manifold and significantly affect the degree to which the exhaust gas is mixed with the fresh air coming into the system. If the exhaust gas and the fresh air are not thoroughly mixed, the full benefits of exhaust gas recirculation (EGR) are not realized. The present invention provides an improved system for injecting exhaust gas into an intake manifold that seeks to improve the mixing of recirculated exhaust gas and fresh air, and maximize the benefits of EGR.
Intake manifolds for an internal combustion engine are provided. In a first embodiment the intake manifold comprises an air inlet; a plenum, the plenum being in fluid communication with the air inlet; at least one primary runner, the at least one primary runner being attached to and in fluid communication with the plenum; and an EGR inlet. The EGR inlet is located near the intersection of the at least one primary runner and the plenum. In a second embodiment, the intake manifold comprises an air inlet; a plenum in fluid communication with the air inlet; at least one primary runner, the at least one primary runner being in fluid communication with the plenum; a flange, the flange having a front side and a back side, wherein the front side of the flange faces the air inlet; and an EGR inlet. The EGR inlet is located on the flange. In a third embodiment, an intake manifold comprises an air inlet; a plenum, the plenum being in fluid communication with the air inlet; a mixing reservoir, the mixing reservoir being in fluid communication with the plenum; a plurality of primary runners, the plurality of primary runners being in fluid communication with the mixing reservoir; and an EGR inlet. The EGR inlet is located in the plenum. In a fourth embodiment, an intake manifold comprises an air inlet; a plenum; a secondary runner, the air inlet being in fluid communication with the plenum via the secondary runner; at least one primary runner, the at least one primary runner being in fluid communication with the plenum; a flow strut, the flow strut being located in the secondary runner; and an EGR inlet. The EGR inlet is located on the strut.